Lecture 7.1: Pathogenesis and Virulence Flashcards
what makes a disease reportable?
highly transmissible
what is a self limiting pathogen?
only affects the person its in; does not spread to others
what is a transmissible pathogen?
can be spread between individuals
for what 3 reasons are diseases reported?
- containment
- lower transmission
- reduction of exposure to others
what is listeria/listerosis?
food borne infection
what causes listerosis?
L. monocytogens
listerosis can take the form of ____ pathogens, causing diseases such as: (5)
- septocaemia
- meningitis
- gastroenteritis
- encephalitis
- mother to fetus transmission
what is septocaemia?
blood borne infection
what is meningitis caused by?
bacteria entering the CSF
where does encephalitis occur?
in the brain
listerosis is a threat for mother-fetus because it is able to __, making it highly virulent
cross central barrier
listeria has mechanisms to interact with host cell during infection; what are some examples?
InlB, ActA LLO
what is InlB?
protein made by bacteria
InlB allows bacteria to be ____ (with respect to host cell)
internalized
how does InlB help bacteria get internalized?
binds to MET and takes over to use clathrin to promote endocytosis
what is MET?
tyrosine kinase
MET is normally the receptor for ____
hepatocyte growth factor (HGF)
in normal cell function, membrane __ is used to promote endocytosis
clathrin
clathrin mediated endocytosis is used to ___ and ___
get nutrients and recycle the membrane
what is listerlysin O? (LLO)
a pore forming toxin
the expression of LLO is ___ regulated so that it is produced ___
tightly; at the exact moment the bacteria needs it
listeria cannot replicate in ____ and must do so in ___
phagosome; host cell cytoplasm
LLO is active at pH ___ (pH of __) and stops at pH ___ (pH of ___)
6 (phagosome); 7(host cytoplasm)
once listeria is endocytosed, it is packaged in a ___
phagosome
in order to replicate, what must happen to the engulfed listeria?
it has to escape the phagosome
activity of LLO is critical to ____ in listeria
replication in host
LLO functions by
dissolving the phagosome that contains listeria
can listeria survive without LLO?
no
disseminating pathogens are able to
spread out to other areas
dissemination results in ____ pathogenesis
increased
disseminating pathogens are associated with
many different diseases
dissemination is made possible by ___ protein
Acet A
what is Acet A?
host actin (f actin) modulating protein
how does Acet A help in dissemination?
hijacks host actin to provide push for intra and intercellular movement
the listeria that travels through cell membranes of adjacent cells while aided by actin is called ___
listeriopod
dissemination causes the literiopod to have a ____ membrane
double
upon invasion of listeriopod into adjacent cell, ___ is activated again
LLO
what causes tuberculosis?
mycobacterium tuberculosis
infection rates of M TB are climbing in ___ countries
developing
M TB is endemic in areas with __ and ___
high population and reduced health care / medicine
the infectious dose of M TB is ____ (around ___bacteria)
extremely low (1-10 bacteria)
reasons why M TB is such a threat
- drug resilient strains
- treatment is long and expensive
- many asymptic carriers
- co-infection can be deadly (HIV)
- existing vaccine is only for short term
treatment of TB can take ___ months
3
it is estimated that ____ people have TB (around ___ of the global population)
2 billion (1/3)
TB is particularly deadly in a co-infection with ___
HIV
what is the vaccine for TB?
bacillus calmate-guerin (BCG)
what is the tubercule?
mass of cells involved in immune response that wall-in bacteria
what is at the core of the tubercule?
macrophages
the mass of cells that forms the tubercule is called a ___
granuloma
the tubercule exists after ____ has occured
M TB replicates within a phagosome
a tubercule develops ____ cells, which are dead
necrotic
some of the bacteria in the tubercule surivive in a ___ form and can ___ in the presence of stress or another pathogen
latent; activate
what is a benefit for the bacteria by being in a tubercule?
avoids active immune response
what is a disadvantage for the host of keeping a bacteria in a tubercule?
can be exposed to sub-lethal conditions, gaining resistance and then later become active
when TB replicates in a phagosome ___ and ___ are recruited
t cells and macrophages
there are ___ within the M TB genome
pathogenicity islands
mycobacteria are highly equipped with
virulence factors
there are ___ pathogenicity islands in M TB required for its pathogenesis
6
the __ strain is ___ components of the PAI and causes it to be ___ virulent
delta RDI BCG; missing; less
in lowered virulence of the delta RDI BCG strain of M TB highlights
the importance of specific PAI for virulence of wild-type (normal) MTB
